C.J. Larson No.1 dam
C.J. Larson No.1
C.J. Larson No.1 is a privately owned dam located in Dewey, South Dakota, along the TR MOREAU river, constructed in 1945. This earth dam stands at a height of 22 feet and spans a length of 600 feet, with a storage capacity of 128 acre-feet. The dam is regulated by the South Dakota Department of Environment and Natural Resources (DENR) and undergoes regular state inspections, enforcement, and permitting processes to ensure its safety and compliance with regulations.
Despite its low hazard potential and current "Not Rated" condition assessment, C.J. Larson No.1 plays a crucial role in water resource management in the area, providing flood control and storage capacity for the surrounding region. The dam has a normal storage capacity of 50 acre-feet and a maximum discharge rate of 360 cubic feet per second. While the dam does not have an Emergency Action Plan (EAP) in place or updated contact information, it continues to be a significant infrastructure for water resource enthusiasts and climate advocates in the region.
Overall, C.J. Larson No.1 serves as a key feature in the St. Paul District of South Dakota, contributing to the management of water resources along the TR MOREAU river. With its historical significance dating back to 1945, this earth dam remains an essential component of the local water infrastructure, highlighting the importance of continued monitoring, maintenance, and regulatory oversight to ensure its long-term functionality and safety for the community and the environment.
Dam data reference
Condition Assessment
- Satisfactory
- No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
- Fair
- No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action.
- Poor
- A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency.
- Unsatisfactory
- A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
- Not Rated
- The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Hazard Potential Classification
- High
- Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
- Significant
- Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environmental damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
- Low
- Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
- Undetermined
- Dams for which a downstream hazard potential has not been designated or is not provided.
Plan around the weather
Same NOAA / yr.no feed Snoflo's iOS app uses. Watch the precipitation column on the meteogram -- rain on the basin upstream typically lifts inflow 24-72 hours later.
Next 5 days, hour by hour
Temperature line with weather symbols on top, snow + rain accumulation as columns, humidity as a dotted line.
5-day forecast table
Every 3 hours, broken out across temperature, snow, rain, humidity, and wind. Each cell is colour-coded relative to the column min/max.
| Time | Condition | Temp (°F) | Snow (in) | Rain (in) | Humidity (%) | Wind (mps) | Wind dir |
|---|---|---|---|---|---|---|---|
| Loading detailed forecast… | |||||||
15-day temperature & precipitation
Daily temperatures, snow, and rain projected over the next two weeks.
Nearby streamflow gauges
USGS streamgauges around C.J. Larson No.1 -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Moreau R Near Whitehorse Sd | 56 cfs | → |
| Grand R At Little Eagle Sd | 45 cfs | → |
| Oak Cr Near Wakpala Sd | 10 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near C.J. Larson No.1.
Campgrounds
Track C.J. Larson No.1 in the Snoflo app
Save this dam as a favorite and get the local NOAA / yr.no forecast plus regional flow context wherever you are.
About C.J. Larson No.1
Where does the data for C.J. Larson No.1 come from?
Structural and regulatory data come from the U.S. Army Corps of Engineers' National Inventory of Dams (NID). Weather forecast comes from NOAA / yr.no -- the same feed Snoflo's iOS app uses.
How often is the report updated?
NID structural data refreshes annually as the Corps publishes updated assessments. The weather forecast refreshes throughout the day.
What does the Low hazard rating mean?
The Corps of Engineers' hazard potential classification grades probable consequences if the dam fails: High = probable loss of human life; Significant = no probable loss of human life but possible economic loss / environmental damage; Low = no probable loss of human life, only minor economic / environmental losses. See the Dam Data Reference card above for the full definitions.
What's "% of normal"?
The current storage value compared to the historical average storage on this calendar day. 100% = right on average; values above 100% mean above-normal storage (wet year); values below mean below-normal (dry year or drought).
Can I get alerts when storage crosses a threshold?
Yes -- alerts are managed in the Snoflo iOS app. Favorite this dam, set a threshold, and you'll get a push the moment conditions cross.
Other water bodies near here
Snoflo-tracked reservoirs and dams within driving distance of C.J. Larson No.1.